Known devices of this kind (see, for example, DE-C 39 32 959, DE-A 40 00 362, and EP-A 0 372 198) have proved successful, especially in extracorporeal lithotripsy, because they offer a tissue-friendly and pain-free form of therapy and guarantee, as well, a specific and effective detection of such objects as ureter and kidney stones.
However, the desire to be able to work even more effectively in specific application areas (e.g., the destruction of deep-lying ureter stones) prompts a need for additional power reserves (RC) regarding sound energy. In principle, other therapy forms (e.g., the stimulation of bone tissues and the treatment of pseudoarthritis) will also require higher powers than were possible up to now.
Increases in power are attained by applying new and improved piezo-ceramics or also by optimal acoustic adaptations, but these are, in general, relatively expensive. Further, the power of devices can also be increased by increasing the high-voltage impulses that drive the transducer elements. Increasing the high-voltage impulses is achieved only at the expense of the lifespan of the transducer elements. It also places maximum demands on the isolation efficacy because the contacts and electrodes of the transducer elements can no longer be reliably isolated electrically with respect to each other. In addition, when high-voltage impulses are increased, the power of the device can only be increased to a limited degree, because otherwise the intensity of the electrical field between the contacts of the transducer elements would become too high. Furthermore, the regulation and changes in length of the transducer elements would no longer be proportional to the applied voltage, and finally, the ceramic could be destroyed.